In related U.S. Pat. Nos. 4,822,398; 4,883,527; 4,909,819; and 4,957,531, a method and apparatus for bending and quenching a heated glass sheet is disclosed. Therein, a pair of spaced opposed platens is provided for controlled bending of the heated glass sheet and its subsequent quenching to impart a specific shape and desirable mechanical characteristics in the bent glass sheet
As these apparatus are operated, drive wheels engage the heated glass sheet and provide oscillated movement of the glass sheet during platen deformation that provides the bending. This movement of the glass sheet back and forth during the bending has resulted in a mechanical distortion, commonly referred to as roller-wave, being established in the subsequently tempered, bent glass sheet. This mechanical distortion decreases the optical quality of the bent glass sheet and such distortion becomes especially noticeable with the bending and tempering of large architectural glass sheet pieces.